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Feofanov AK, Oboznov VA, Bol'Ginov VV, Lisenfeld J, Poletto S, Ryazanov VV, et al. Implementation of superconductor/ferromagnet/ superconductor. Nat Phys. 2010;6(8):593–7.
Abstract: High operation speed and low energy consumption may allow the superconducting digital single-flux-quantum circuits to outperform traditional complementary metal-oxide-semiconductor logic. The remaining major obstacle towards high element densities on-chip is a relatively large cell size necessary to hold a magnetic flux quantum Φ0. Inserting a π-type Josephson junction in the cell is equivalent to applying flux Φ0/2 and thus makes it possible to solve this problem. Moreover, using π-junctions in superconducting qubits may help to protect them from noise. Here we demonstrate the operation of three superconducting circuits-two of them are classical and one quantum-that all utilize such π-phase shifters realized using superconductor/ferromagnet/superconductor sandwich technology. The classical circuits are based on single-flux-quantum cells, which are shown to be scalable and compatible with conventional niobium-based superconducting electronics. The quantum circuit is a π-biased phase qubit, for which we observe coherent Rabi oscillations. We find no degradation of the measured coherence time compared to that of a reference qubit without a π-junction.
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Ozhegov RV, Gorshkov KN, Gol'tsman GN, Kinev NV, Koshelets VP. The stability of a terahertz receiver based on a superconducting integrated receiver. Supercond Sci Technol. 2011;24(3):035003.
Abstract: We present the results of stability testing of a terahertz radiometer based on a superconducting receiver with a SIS tunnel junction as the mixer and a flux-flow oscillator as the local oscillator. In the continuum mode, the receiver with a noise temperature of 95 K at 510 GHz measured over the intermediate frequency (IF) passband of 4-8 GHz offered a noise equivalent temperature difference of 10 ± 1 mK at an integration time of 1 s. We offer a method to significantly increase the integration time without the use of complex measurement equipment. The receiver observed a strong signal over a final detection bandwidth of 4 GHz and offered an Allan time of 5 s.
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Yagoubov P, Hoogeveen R, Torgashin M, Khudchenko A, Koshelets V, Suttiwong N, et al. 550-650 GHz spectrometer development for TELIS. In: Proc. 17th Int. Symp. Space Terahertz Technol.; 2006. p. 338–41.
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Koshelets VP, Borisov VB, Dmitriev PN, Ermakov AB, Filippenko LV, Khudchenko AV, et al. Integrated submillimeter receiver for TELIS. Joint International Workshop “Nanosensors and Arrays of Quantum Dots and Josephson Junctions for space applications”, 10th International Workshop “From Andreev Reflection to the Earliest Universe”. 2006.
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Koshelets VP, Khudchenko AV. Analysis of spectral characteristics of a superconducting integrated receiver. J. Communications Technol. Electron.. 2006;51(5):596–603.
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Koshelets VP, Ermakov AB, Filippenko LV, Khudchenko AV, Kiselev OS, Sobolev AS, et al. Superconducting integrated submillimeter receiver for TELIS. IEEE Trans. Appl. Supercond.. 2007;17(2):336–42.
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Hoogeveen RWM, Yagoubov PA, de Lange A, Selig AM, Koshelets VP, Ellison B. N., et al. Superconducting integrated receiver development for TELIS. In: Proc. 12th International Symposium on Remote Sensing. Bruges, Belgium; 2005.
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Vaks VL, Kurin VV, Pankratov AL, Koshelets VP. Investigation of spectral properties of phase-focked flux flow oscillator [abstract]. In: ISEC. Netherlands; 2005. PD-04.
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Koshelets VP, Dmitriev PN, Ermakov AB, Filippenko LV, Sobolev AS, Torgashin MY, et al. Superconducting flux-flow oscillators for THz integrated receiver [abstract]. In: Presented at the second Franco-Russian Seminar on Nanotechnologies. Lille, France; 2005.
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Mygind J, Samuelsen MR, Koshelets VP, Sobolev AS. Simple theory for the spectral. linewidth of the mm-wave Josephson flux flow oscillator [abstract]. In: Pi-shift Workshop “Physics of superconducting phase-shift devices”. Ischia, Italy; 2005. p. 22.
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